Purpose: Depressive symptoms are highly prevalent in patients with chronic obstructive pulmonary disease (COPD) and have been associated with poor outcomes. Developing a concise questionnaire to measure depressive symptoms in COPD patients is needed in outpatient settings. We evaluated the clinical usefulness of a concise two-question instrument to assess depressive symptoms in patients with COPD.
Methods: The study was conducted as a cross-sectional analysis in patients with COPD. All patients completed a self-reported questionnaire consisting of the two-question instrument, as well as a shortened version of the Center for Epidemiologic Studies Depression Scale (CESD-10) to measure depressive symptoms. Performance of the two-question instrument was evaluated using the results for CESD-10 as standard. We also measured patients' health-related quality of life using the Medical Outcomes Study 8-Item Short-Form Health Survey (SF-8) to determine whether the instrument was related to SF-8.
Results: Sensitivity of the two-question instrument in the detection of depressive symptoms was 73.3 % (95 % confidence interval [CI] 51-95.7), specificity was 73 % (95 % CI 58.7-87.3), and area under the receiver operating characteristics curve was 0.73 (95 % CI 0.59-0.87). When study patients were divided into two groups with a cutoff of 1 point on the two-question instrument, scores for all subscales of the SF-8 except "bodily pain" were significantly lower in patients with than without depressive symptoms.
Conclusions: This concise two-question instrument is useful as assessment of depressive symptom in patients with COPD in busy outpatient settings.